This invention relates to gasoline additives and more particularly to gasoline compositions containing small amounts of arylfluoroalkanes.
In recent years, because of the detrimental effect caused to both the environment and to the automobile engine itself by the use of highly leaded, high octane gasolines, a concerted effort has been made to reduce the octane requirements of the automobile engine. Because the addition of lead has, to date, been the most economical way of increasing the octane rating of a gasoline, its use has remained widespread throughout the industry where high octane gasolines are required. However, gasoline companies are marketing higher percentages of low leaded gasolines than ever before, such gasolines generally having a lower octane rating and being unsuitable for use in high compression engines.
On account of air pollution considerations, automobile manufacturers have turned almost exclusively to lower compression engines. With the rate at which high compression engines are presently decreasing, which is estimated at 7,000,000 cars a year, high performance, high compression automobiles may be substantially phased out by the end of the decade. This should result in a corresponding decrease in the sale of high octane gasolines, making it uneconomical for the major gasoline companies to even market such high octane products. Nevertheless, there are presently about 35 million high compression engine cars in the United States and its foreseeable that a substantial number of high compression, high performance automobiles will remain on the road as long as the proper fuel is available to run them. From the foregoing, it should become apparent that a fuel additive which will reduce the octane requirements of engines thereby allowing them to operate efficiently on low octane fuels may become highly desirable if high octane fuels are no longer available for purchase.
Although there are many additives in gasoline for many reasons, such as combustion moderators, lubricants, detergents, solvents, dehydrants, etc., such additives are usually not intended to substantially reduce the octane requirement of the engine and thereby permit the use of a much lower octane rated fuel than that recommended for the particular engine. Included in such additives are fluorinecontaining compounds. For example, in U.S. Pat. No. 2,186,916 to Gaylor, disclosed is an engine lubricant containing fluorinated mineral or vegetable oils which are stable below and boil above 200.degree.C. These fluorinated compositions are employed in relatively large amounts, from about 5 to about 60% by weight of the lubricant composition. In U.S. Pat. No. 2,291,166 to Maag, fluorinated hydrocarbons, sufficiently stable as not to become detrimentally chemically active or decompose under operating conditions are utilized for the lubrication of internal combustion engines.
Some prior art patents have also proposed the use of fluorinated aromatic compounds as a fuel additive. However, fluorinated aromatic compounds, when recommended for use as a fuel additive, have generally been selected on account of their solvent or lubricating properties. In U.S. Pat. No. 2,214,768 to Lincoln, halogenated ring compounds are recommended for use in a fuel system for their lubricating properties, which includes carbon solvent action. In order to operate effectively as a lubricant, it is pointed out that the halogenated compounds selected should have a sufficiently low vapor pressure to remain as a liquid and not undergo combustion upon volatilization of the fuel in the combustion chamber. Likewise, in U.S. Pat. No. 2,281,598 to Prutton, which discloses fluorinated benzenes for use as a fuel additive to dissolve carbon deposits from the walls of an internal combustion engine, combustion of the solvent cannot be tolerated. For this reason it is recommended that in the selection of halogenated aromatic compounds, the halogen he attached to the benzene ring to insure stability. Finally, U.S. Pat. No. 2,838,387 to Rudel, broadly discloses aryl alkanes which are at least partially fluorinated for use as a fuel additive. However, since the object of adding such compounds to the fuel is again to dissolve carbon deposits, it is recommended that the compounds selected be substantially non-volatile, non flammable and thermally stable. To obtain these properties, the compounds of Rudel must have a boiling point of at least 100.degree.C and preferably greater than 150.degree.C, with at least 14 and preferably greater than 22 carbon atoms. The preferred compounds are high molecular weight polymers which will neither volatilize nor thermally decompose during the engine cycle.
In contrast, it is an object of this invention to provide a fuel additive which will readily volatize and pyrolize in the combustion chamber of a high compression engine.
It is another object of this invention to provide a fuel additive which will permit the use of lower octane gasolines for higher compression engines as well as prolong spark plug life and contribute to a cleaner engine.
It is yet another object of this invention to provide a fuel additive which may be added directly to the fuel tank by the consumer and which will chemically decompose during the engine cycle.